Casting method



Aug. 19, 1958 J. B. BRENNAN CASTING METHOD Filed May 2, 1955 2Sheets-Sheet 1 INVENTOR. JOSEPH 8. Eff/ IVAN ArroeMeKS Aug. 19, 1958 J.B. BRENNAN CASTING METHOD 2 Sheets-Sheet 2 Filed May 2, 1955 9 ATTOPMFVSUnited States Patent fiiice 2,847,737 Patented Aug. 19, 1958 CASTINGMETHOD Joseph B. Brennan, Cleveland, Ghio Application May 2, 1955,Serial No. 505,100 '1 Claim. (CL 22--57.2)

This invention pertains. to the casting of metal slab, strip. metal andlaminated metal and apparatus therefor. This. application is acontinuation-in-part of my co-pending application Serial No. 147,466,filed February 18, 1950, now Patent No. 2,714,235.

According to this invention I move for example a partly immersed annularstrip or ring of metal through a pool of molten metal and through a dieadjacent thereto, and thereby cast a layer of the molten metal along andaround the small diameter of said annular strip or ring of metal, whichlayer is chilled progressively around said annular strip or ring as itpasses through said die, so that the annular strip or ring emerges fromthe die coated with a layer of the previously molten metal of athickness corresponding to the spacing of the cooling die inner Walls.with the exterior of the small diameter surface of the annular strip orring.

According to this invention I also move a slab or bar of metal throughone or more successive containers and chilling dies to cast a layer orsuccessive layers of metal thereonto to thereby buildup thecross-section size thereof. In this connection, laminated metal stripmay be continuously cast by moving an endless core successively into acontainer having molten metal therein and through a chilling die andthen into a container having a lower melting point metal therein andthrough another adjoining chilling die, and by stripping the compositemetal strip from said core.

Referring to the drawings herewith:

Figure l is a section of mechanism for carrying out this invention.

Figure 2 is a section of large annular ring with guide anddrive rollsthereabout.

Figure 3 is a cross-section of producing a multiple series of invention.

Figure 4 is an alternate shape of large annular form with metal sheaththereover for producing two strips of flat strip metal by parting thesheath along two lines instead of just one.

Figure 5 is a cross-section view of an apparatus for applying successivelayers of cast metal onto a metal bar or slab.

Figure 6 is a cross-section view of an apparatus similar to that ofFigure 1 except showing the continuous production of laminated stripmetal.

Referring to Figure 1:

The annular ring 8 which may be of chromesteel or graphite, or acombination of heat resisting rigid materials, rotates counter clockwisethrough funnel 7, having a pool of ceramic heat resisting partingcompound paste therein which deposits over ring 8 as it rotatestherethrough and fills the groove 13 therein. A flame deposited carbonlayer will also serve as a parting compound for coating ring 8 prior toentering the molten metal 1 in funnel crucible 4.

The groove 13 may be eliminated, but is used if gear drive is chosen torotate the. annular ring 8, and also a large annular ring for wires,according to this 2 serves as an added guide for ring 8 as well as arelief for subsequently applied slitter.

1 represents a pool of molten metal in a holding crucible 3, maintainedat a constant temperature by heater 17, which crucible supplies moltenmetal through valve 2 in discharge spout 19 leading to constant levelcrucible 4 wherein a constant head of molten metal 1 is, maintained bykeeping the level so that it overflows into a third crucible 5.

The annular ring 8 is driven by rolls 10 shown here operating in groove13', which may have gear teeth therein, or may be smooth if frictiondrive will sufiice. The. annular ring 8 is fluid cooled die 21, Fig. 1,and downward through the pool of molten metal 1 in funnel shapedcrucible 4 by rolls 9.

Gas flames 17 maintain the metal 1 in funnel crucible 4 at a constantmolten temperature and the fluid coolant sprays it? acts as additionalcooling devices for the emerging layer of metal about annular ring 8.

When and as the annular ring 8 passes through the molten metal 1 incrucible 4 a skin of metal is chilled thereabout due to the heatabsorbing capacity of ring 8 which is thinner than the spacing of thedie 21 from the exterior surface of annular ring 8, and as this skinadvances into die 21 it carries with it exteriorally a layer of moltenmetal which is instantly and constantly chilled by fluid cooled die 21so" that the metal about annular ring 8 as it emerges from die 21retains its shape, and though it be for example red hot as it emerges,is none the less in the shape of a sheath about the annular ring 8section as it leaves die 21. The fluid sprays 18 further solidify andchill the sheath. 20 of metal surrounding annular ring 8 as the ring 8advances downward after V leaving die 21.

Two sets of rolls are situated above and below the crucible 4 and die 21to accurately retain the spaced relation of ring 8 and die 21.

The rotary saw 12 rotated against the inner circumference of ring 8serves to slit the sheath 20 of metal from around the annular ring 8 asthe ring 8 with the sheath 20 thereon revolves downward and the strippershoe 14 with rolls 15 strip the metal sheath 20 after slitting, and rollit into a flat shape which is made into a coil 16 by mechanism 22,having a power driven clutch thereon with constant speed and tension.This saw 12 may be operated on the outer circumference of the ring 8aiso, or otherwise if desired.

Referring to Figure 2: r

10 represents a roll having teeth 13 therein which engage with teeth ingroove 13 of annular ring 8 to drive the annular ring 8 through themolten metal and die, which forms the metal coating 20 over the ring 8.9 represents an exterior guide roll for annular form 8.

Referring to Figure 3:

8 represents an alternate design of large annular form cross-sectionwhereby thick sections 20 and very thin sections 20a may be castthereabout as a sheath which may be easily parted into multiplewires.

Referring to Figure 4:

8 represents an alternate cross-section for large annular rotating form8, having a sheath of metal 20 thereover, which may be readily slit atedges 23 thereof to make strips which may be rolled flat and coiled withless distortion than if a circular cross-section is used in makingannular ring 8.

Thus for example, if I use an annular strip or ring of heat resistingalloy metal or ceramic material, say 72" large diameter and 1" smalldiameter of the material, and pass it through the bottom of a cruciblehaving a pool of molten Cu or Al therein having a bottom die in saidcruciblecompris'ing a thin water cooled copguided and retained centrallythrough,

per shell Ms" larger in interior diameter than the small diameter of theannular strip or ring, and conforming in A spaced shape thereabout for adistance of a few inches or less, and force the annular strip or ring byrotation down and through the aforesaid pool of molten metal and throughsaid water cooled die in exact spaced relation to said die, a layer ofmolten metal will cling to the exterior of ,the small diameter of theannular strip or ringand form a coating thereabout, which coating can beslit and stripped therefrom and formed into a continuous flat coil ofmetal which was previously molten.

It is to be understood that the sleeve or coating cast and cooled aboutthe moving rod or shape may be slit into as many strips of metal asdesired for removal.

The cross-sectional shape of the rod moved through the pool of moltenmetal may be of any desired shape to produce the desired shape of stripmetal.

Thus screw shaped grooves or longitudinal grooves may be put into theannular strip about which the sleeve or layer is cast, so that slittingand removal is made easier and less waste is encountered.

Grooves may extend longitudinally of the bar about which the sleeve iscast, which will fill with cast metal and very thin sections will becast between the grooves, permitting easy slitting into one or morestrips.

Where the saw slitter functions it is desirable to have a groove topermit clearance for the same, and the metal cast therein is removed bythe saw. If on the other hand a very thin section is produced bycross-sectioned shape of the large annular strip about which the metalis cast, stripping and slitting may be accomplished by a parting tool.

Wires may be produced by using a large annular casting strip having manygrooves therein which will be filled with metal with only extremely thinjoining sections. The die and annular strip could be so closely fittedthat only wires would be cast if one chooses to maintain extremely closetolerances between the exterior of the grooved large annular ring andthe inside diameter of the cooling die.

It is also to be understood that the molten metal pool about the largeannular strip may be piped thereabout through a conduit leading from aremote metal crucible under pressure if desired in accordance with thisinvention.

In any case, according to this invention a sleeve of cast metal isforced and carried out of the cooling die by the adherence of suchsleeve of cast metal to an interior moving bar or strip to which thecast metal sleeve has greater adherence than that evinced between thecast metal sleeve and the cooling die.

The apparatus of this invention may be enclosed in an inert ornon-oxidizing atmosphere chamber.

Coating of the annular strip around which the metal is cast to preventnon-adherence may be done with graphite or other anti-stick materials.

If high frequency is used to maintain the temperature of the pool ofmolten metal the large annular form into which the coating is depositedmay be made of a material not highly responsive to the frequency of theheating coils so that economy of heating is secured. A composite annularcasting form may also be used, such as a ceramic coated metallic rod ora corrosion resistant lamination or metallic overlay may be applied tothe long annular casting form to lend stability thereto.

It is preferable according to this invention to keep the temperature ofthe long annular strip or ring at all points on its body at less thanthe melting point of the metal being cast, and this is even true as thebest procedure at the section where the strip passes through the moltenmetal. This saves energy and also lessens corrosion on the large annularstrip as well as permitting greater speed and higher production rates.

Laminations may be cast by this method and apparatus by having two ormore pots of metal and dies through 4 which the bar or annular strip ispassed and coated sequentially prior to stripping.

It is preferred in all cases according to this invention that thecross-sectional tensile strength of the large annular strip or ringwhich is passed through the molten metal and coating die be greater thanthe cross-sectional tensile strength of the deposited metal thereabout.It is the addition of the large annular strips tensile strength whichenables me to overcome the die sticking tendency which heretofore hasprevented the efficient casting of thin constant dimensioned continuousmetallic strip. The cross-sectional strength of the large annular stripor ring must be such under the temperature to which it is controlled orlimited as by cooling fluid, that it may be withdrawn through the chilldie even though there is a considerable tendency for the chilled metalto adhere and stick to the inner die wall.

Gear teeth for rotating may be incorporated in the inside periphery ofthe large annular strip or ring onto which the thin layer of moltenmetal is cast. These teeth are preferably coated or filled with ceramicnonsticking material prior to passing through the molten metal.

The heat absorption and radiation capacity of the large annular strip orring must be of such an order that it may be constantly and continuouslypressed through the molten metal pool and the chilling fluid cooled dieand be maintained constantly at a temperature sufficiently lower thanthe melting point of the metal being cast to cause a skin of moltenmetal to solidify therearound constantly without fusion thereto.

It is also contemplated according to this invention to form a sheet ofpre-fabricated metal as steel around a bar or shape or large annularstrip or ring, by rolling such strip metal thereover and fittingtherearound tightly, or even welding the abutted edges thereof, thenpassing this sheath with the strip or ring inside through the pool ofmolten metal and casting thereabout a layer of molten metal andsolidifying said layer in the chilling die whereby a laminated fusedlayer as of copper may be fused and evenly deposited to the superposedand pre-formed tubular shape and thereafter stripping the unitarylamination from the large annular ring.

Referring now to Fig. 5, there is shown a container 30 and an adjoiningchilling die 31 through which a steel or other metal bar or slab 32 of3" x 24" cross-section size for example is adapted to be moved to have alayer of molten steel or other metal in container 30 applied thereto andsolidified in die 31. This casting operation may be repeated any numberof times finally to produce a steel bar, for example of say 24" x 24",or other crosssection size. Preferably a 3" thick layer of metal isapplied at each casting operation in the foregoing example, but,obviously the cast layer thickness may be more than or less than 3". Ihave found that 4" is approximately the greatest thickness ofpenetration when using Water-cooled dies 31 without resulting incavities and piping in the successsive cast layers.

Referring now to Fig. 6, there is shown therein an apparatus like thatof Fig. 1 except that one or more additional containers 40 and adjoiningdies 41 are employed to produce laminated strip metal. The highermelting point metal or alloy is first cast onto the ring or core 8 asthe core passes through container 4 and adjoining water-cooled die andthen another metal or alloy of lower melting point is cast onto thefirst metal layer as the core 8 and metal thereon passes throughcontainer 40 and die 41. After the two-layer casting emerges from die 41it may have additional layers cast thereon, and finally the saw 12 slitslaminated product for removal in strip or wire form from the core 8. Asan example, steel may first be cast onto core 8 and then bronze is castonto the congealed steel layer. As another example, an aluminum oraluminum alloy layer may be first cast followed by casting of a bearingmetal or alloy such as a 98% lead 2% silver alloy, for example.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in the following claim, or the equivalent of such, beemployed.

I therefore particularly point out and distinctly claim as my invention:

The method of casting composite strip metal comprising the steps ofcontinuously and cyclically passing a core through a first bath ofmolten metal and an adjoining chilling die to continuously cast a firstlayer of molten metal on said core; shaping and cooling said first layerof metal on said core as it passes through said die to cause the metalto cling thereto by shrinkage; continuously and cyclically passing saidcore and first layer of metal thereon through a second bath of moltenmetal and another adjoining chilling die to continuously cast a secondlayer of molten metal on the first layer of metal on said core; shapingand cooling said second layer of metal on said first layer as it passesthrough the die adjoining said second bath of molten metal to cause saidsecond layer of metal to shrink onto said first layer of metal; andcontinuously removing the composite strip metal comprising said firstand second layers of metal from said core prior to continuously andcyclically passing said core through said first and second baths ofmolten metal and said adjoining chilling dies.

References Cited in the file of this patent UNITED STATES PATENTS223,077 Tasker Dec. 30, 1879 1,948,505 Bray Feb. 27, 1934 2,301,902Merle Nov. 10, 1942 2,348,178 Merle May 2, 1944 2,433,903 Hensel et a1Jan. 6, 1948 2,664,605 Beste Jan. 5, 1954 2,714,235 Brennan Aug. 2, 1955FOREIGN PATENTS 711,133 Germany Sept. 26, 1941 844,806 Germany July 24,1952

